Crème Fraîche
Crème fraîche is cream that has been thickened and given a mild tang by bacterial culture, similar to sour cream but higher in fat (typically 30-45%) and less sharply sour.
Its higher fat content lets it be simmered into sauces and soups without curdling, unlike lower-fat sour cream. It's a staple in French cooking (béchamel-based sauces, quiches), used as a cooling counterpoint to spicy dishes in Mexican and Central American cooking, and appears in Scandinavian savory and baked preparations. It pairs well with dill, chives, tarragon, smoked or cured fish, and berries.